ID   KGX18_CENEL             Reviewed;          42 AA.
AC   P0C893;
DT   14-OCT-2008, integrated into UniProtKB/Swiss-Prot.
DT   14-OCT-2008, sequence version 1.
DT   25-MAY-2022, entry version 27.
DE   RecName: Full=Potassium channel toxin gamma-KTx 1.8 {ECO:0000303|PubMed:18338253};
DE   AltName: Full=CeErgTx5 {ECO:0000305};
DE            Short=CeErg5 {ECO:0000303|PubMed:18338253};
OS   Centruroides elegans (Bark scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Centruroides.
OX   NCBI_TaxID=217897;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, MASS SPECTROMETRY, SUBCELLULAR LOCATION, AND
RP   NOMENCLATURE.
RC   TISSUE=Venom;
RX   PubMed=18338253; DOI=10.1007/s11064-008-9634-8;
RA   Restano-Cassulini R., Olamendi-Portugal T., Zamudio F., Becerril B.,
RA   Possani L.D.;
RT   "Two novel ergtoxins, blockers of K(+)-channels, purified from the Mexican
RT   scorpion Centruroides elegans elegans.";
RL   Neurochem. Res. 33:1525-1533(2008).
RN   [2]
RP   FUNCTION, AND SYNTHESIS.
RX   PubMed=29483648; DOI=10.1038/s41594-018-0033-9;
RA   Correnti C.E., Gewe M.M., Mehlin C., Bandaranayake A.D., Johnsen W.A.,
RA   Rupert P.B., Brusniak M.Y., Clarke M., Burke S.E., De Van Der Schueren W.,
RA   Pilat K., Turnbaugh S.M., May D., Watson A., Chan M.K., Bahl C.D.,
RA   Olson J.M., Strong R.K.;
RT   "Screening, large-scale production and structure-based classification of
RT   cystine-dense peptides.";
RL   Nat. Struct. Mol. Biol. 25:270-278(2018).
CC   -!- FUNCTION: Blocks in a reversible manner human and rat Kv11.1/KCNH2/ERG1
CC       potassium channels (PubMed:18338253). Also completely and irreversibly
CC       blocks rat Kv11.2/KCNH6/ERG2 and human Kv11.3/KCNH7/ERG3 channels
CC       (PubMed:18338253). Also weakly inhibits Kir2.1/KCNJ2 and Kv1.2/KCNA2
CC       potassium channels (PubMed:29483648). {ECO:0000269|PubMed:18338253,
CC       ECO:0000269|PubMed:29483648}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:18338253}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:18338253}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:Q86QT3}.
CC   -!- DOMAIN: Has the CSalpha/beta fold, which comprises one or two short
CC       alpha helices connected to anti-parallel beta-sheets stabilized by
CC       three or four disulfide bonds. {ECO:0000250|UniProtKB:Q86QT3}.
CC   -!- MASS SPECTROMETRY: Mass=4775.0; Method=Unknown;
CC       Evidence={ECO:0000269|PubMed:18338253};
CC   -!- MISCELLANEOUS: Does not affect human Kv11.2/KCNH6/ERG2.
CC       {ECO:0000269|PubMed:18338253}.
CC   -!- SIMILARITY: Belongs to the ergtoxin family. Gamma-KTx 1 subfamily.
CC       {ECO:0000305}.
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DR   AlphaFoldDB; P0C893; -.
DR   SMR; P0C893; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0019870; F:potassium channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   Gene3D; 3.30.30.10; -; 1.
DR   InterPro; IPR012622; Ergtoxin.
DR   InterPro; IPR036574; Scorpion_toxin-like_sf.
DR   Pfam; PF08086; Toxin_17; 1.
DR   SUPFAM; SSF57095; SSF57095; 1.
DR   PROSITE; PS60026; ERGTX; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Knottin; Neurotoxin; Potassium channel impairing toxin; Secreted; Toxin;
KW   Voltage-gated potassium channel impairing toxin.
FT   CHAIN           1..42
FT                   /note="Potassium channel toxin gamma-KTx 1.8"
FT                   /evidence="ECO:0000269|PubMed:18338253"
FT                   /id="PRO_0000352491"
FT   DISULFID        5..23
FT                   /evidence="ECO:0000250|UniProtKB:Q86QT3"
FT   DISULFID        11..34
FT                   /evidence="ECO:0000250|UniProtKB:Q86QT3"
FT   DISULFID        20..39
FT                   /evidence="ECO:0000250|UniProtKB:Q86QT3"
FT   DISULFID        24..41
FT                   /evidence="ECO:0000250|UniProtKB:Q86QT3"
SQ   SEQUENCE   42 AA;  4782 MW;  9BE5F5145BF93360 CRC64;
     DRDSCIDKSR CSKYGYYQEC QDCCKKAGHN GGTCMFFKCK CA